Synthesis of Cis-Cisoid or Cis-Transoid Poly(Phenyl-Acetylene)s Having One or Two Carbamate Groups as Oxygen Permeation Membrane Materials

Three new phenylacetylene monomers having one or two carbamate groups were synthesized and polymerized by using (Rh(norbornadiene)Cl)2 as an initiator. The resulting polymers had very high average molecular weights (Mw) of 1.4–4.8 × 106, with different solubility and membrane-forming abilities. The polymer having two carbamate groups and no hydroxy groups in the monomer unit showed the best solubility and membrane-forming ability among the three polymers. In addition, the oxygen permeability coefficient of the membrane was more than 135 times higher than that of a polymer having no carbamate groups and two hydroxy groups in the monomer unit with maintaining similar oxygen permselectivity. A better performance in membrane-forming ability and oxygen permeability may be caused by a more extended and flexible cis-transoid conformation and lower polarity. On the other hand, the other two new polymers having one carbamate group and two hydroxy groups in the monomer unit showed lower performances in membrane-forming abilities and oxygen permeabilities. It may be caused by a very tight cis-cisoid conformation, which was maintained by intramolecular hydrogen bonds.


S2. Supplemental scheme and figures for the text
Scheme S1. Synthetic route to poly(4) and poly(5).

S3.1 The crystallinity of poly(3) and poly(4) membranes
The poly(3) membrane which took loose cis-transoidal racemic helical main chains shows much lower crystallinity than that of poly(4) whose main chain took regular cis-cisoidal helical conformation. The columnar diameter D and lattice spacing of poly(3) membrane are smaller than that of poly(4) due to the loose cis-transoidal conformation. Figure S24. XRD of poly(3) and poly(4) in membrane state.

S3.2 The morphology of poly(3) and poly(4) membranes
The surface morphology of the poly(3) and poly(4) membranes were measured by Scanning Electron Microscope (SEM) which were recorded on a HITACHI S-4300 electron microscope. As shown in Figure S25, the surface of poly(3) membrane is more smooth than that of poly(4). The higher solubility of poly(3) gave a good dense membranes without defect. Figure S25. The SEM images of (a) poly(4) and (b) poly(3) membranes.

S4. Unsuitability of the monomers for helix-sense-selective polymerization
As we described in the introduction part, we reported before that monomer 4 having two hydroxymethyl groups was suitable for helix-sense-selective polymerization because the resulting polymer could tight cis-cis helicity stabilized by intramolecular hydrogen bonds between OH groups [13]. However, the three new monomers 1-3 were not suitable for helix-sense-selective polymerization because no Cotton effect was observed in the resulting three new polymers (poly(1)-poly (3)). Although monomers 1 and 2 containing two hydroxy groups similar to monomer 4, by the introduction of the carbamate group, the polarity of the polymers became higher and therefore they could soluble only in polar solvents where hydrogen bonds were not stable. As a result the intramolecular hydrogen bonds between OH groups in the polymer were disrupted and became weaker (Figure 3). Therefore, it could not maintain one-handed helicity, although they had tight cis-cisoidal conformations. In order to discuss hydrogen bonds in the new polymers, the IR spectra of poly(1) and poly(2) together with poly (4) which has two hydroxy groups in their monomer unit were measured in CHCl3 (2.00 mmol/L) (Figure 3). The stretching vibration bands of O-H were observed around 3336 and 3337cm -1 for poly(1) and poly(2), respectively. Since the stretching vibration band of O-H for poly(4) having no carbamate groups appeared at 3309 cm -1 , the introduction of the carbamate groups weekend the hydrogen bonds between the hydroxy groups. As results, poly(1) and poly(2) prepared by using chiral cocatalysts had no CD peaks different from poy(3) because their main chain stability was a littler lower.
In the case of poly(3), the two bulky t-butyl groups may prevent the forming of intramolecular hydrogen bonds between NH and CO groups (Figure 4). Therefore, no Cotton effect could be found in poly(3). As another possible reason for the unsuitability for helix-sense-selective polymerization of the carbamate-containing monomers, the interaction between the carbamate group and rhodium catalyst could have affected the formation of stable one-handed helical main chain or the function of the polymerization catalyst.